US1975886A

US1975886A - Plastic packing stuffing-box

Info

Publication number: US1975886A
Application number: US504070A
Authority: US
Inventors: Harley T Wheeler
Original assignee: Individual
Current assignee: Individual
Priority date: 1930-12-22
Filing date: 1930-12-22
Publication date: 1934-10-09
Anticipated expiration: 1951-10-09

Description

H. T. WHEELER PLASTIC PACKING STUFFING BOX IN V EN TOR.

Oct. 9, 1934. E H. T. WHEELER 1,975,886

PLASTIC PACKING STUFFING BOX.

Filed Dec- 22, 1950 2 Sheets-Sheet? 112 sazLo p1 1134. 2810.;

INVENTOR.

1397 g WA Patented Oct. 9, 1934 1525,83;

STATES My invention relates to improvements in apsectioning of the sleeve 6. A series of right and plying plastic packing to stufiing-boxes and its left hand multiple square grooves are formed chief advantage is a capability of securing a tight in the bore of the sleeve 6 making the grooves joint under high pressures when subjected to ex- I 22 and leaving the

lands

23 and 24 between the 5. cessive temperatures or adverse chemical reacgrooves. The face of each groove which, is dition. rected toward the pressure is cut at an acute am- This particular invention consists of forming gle W th t e Su ace of the p forming a right and left-hand helical grooves in the sursharp lip. If h ran i fr m v um to presface of a stuihng-box and shaping them so that Sure, a p W he formed on each of the pp 10 the plastic packing injected Willmaintain a tight f Th pr j cti of h he is shown on one joint under the extremes of quick rise and fall r v n y to avoid f i n f dotted l n of pressure in the presenceof harsh media, by A pa s 29 is made the entire length of the properly maintaining the density and position or Sleeve 6 a d Connected t the grOOVeS 22 at a th m ti te i L convenient point near the source of pressure.

15 A further advantage of this invention is the Th passage 0 does n in r any other p use of a spring-loaded-reservoir to inject or withtion of the grooves nor the outer surface of the draw packing from the grooves, according to the sleeve 6. vibration or position'of the rod. R urnin n w to Fi ur 1, a di c 9 havin A still further and important advantage is the cl arance ar u d t p u 2 a d being a loose 20 use of a sampler connected to an injection point fit t the S U fi -bOX Chamber 1, is inserted bein t g ooves, whereby Samples of the packing fore the sleeve 6 to close the intersection of the in use can be withdrawn and examined, coincigrooves 22 With the end of the Sleeve Such dent with the injection of new packing, 'withintersections being indicated in Figure 3. A out stopping the machine. Y gasket 7 is inserted between the disc 9 and the 25 Further objects and advantages of this invenguide bushing 8 to make a pressure tight joint tion will appear With the description of the conbetween the bottom of the chamber 1 and the struction which follows, accompanied by the packing n in n m ly. The joints b drawings, wherein: tween the

respective parts

3, 6 and 9 are suitably Figure 1 is a cross-section of; a stufiing-box p p to pr v n l aka f h r h p k- 3o constructed according to this invention. 'ing or the liquid under pressure. 1

Figure 2 is a cross-section of the plastic cone An annular passage 19, made in the body of tainer. the gland 3 intersects that face of the [gland Figure 3 is an end viewiof the plastic con- Which is adjacent to the sleeve 6, so connecting tainer. with the helical grooves 22 made in the sleeve 6. 35 Figure 4 is a cross-section of the sampling The passage 29 is extended thru the gland 3 9o device. and terminates in a threaded hole, a sampler Figure 5 is an outer end view of the sampler. body 25 being screwed therein. The rotor 26 Figure 6 is a cross-sectional View of the and a cap 25 are parts of the sampler which will sampler. be explained later in more detail. A dowel 10 4a Figure '7 is an innerend View of the sampler. align th gland 3 With the eve 6 So that a Referring now especially to Figure. 1, a repreproper relation of parts is maintained. Refersentation of a reciprocating plunger or rod in a' ring W o Figure the section of t e stuffing-boxbuilt according to this invention; helical grooves 22 with the end of sleeve 6 are the frame extension 1 contains the stufilng-box indicated and the effect of the sharp lip 28 is also 45 chamber into which the plunger 2 travels to shown. The passage 20 is located between the compress a liquid for example, the plunger, 2 surfaces of grooves 22 and the outer surface of being guided and aligned by the bushing 8. A the sleeve 6. The dowel hole 10a is the location sleeve 6 is the plastic container used in this for the dowel 0 Sh w in Figure device and has a loose fit in the stuffing-box A continuation of passage 19 leadsthru the 5g chamber 1, being held in place by the gland 3. "flange of the gland 3 and in an upward direction,

Gland 3 is tightened by the studs land the ending in athreaded hole. A pipe 11 is threaded nuts 5. into the termination of passage. 19, and then Before completing the description of the asinto a valve body 12, passage 19 thereby being sembly as shown in Figure 1, itappears necescontinued from the gland 3 into the valve body 55 sary to refer to Figure 2, alengthwise cross- 12. The upper part of the valve body 12 is formed into a reservoir, the outside of the latter being threaded to receive a cap 14. A needle valve 13 is also threaded into the valve body 12 and intersects the passage 19 so that the latter may be closed or opened. The cap 14 is threaded to receive an adjusting nut 16 thru which the piston rod 17 passes to be attached to the piston 15, the latter residing in the bore of the reservoir which has been formed in the body 12. Y A spring 18 provides means to vary the tension of the piston against any material placed under it. The

respective parts

12, 13, 14, 15, '16, 1'7 and 18 constitute a spring-loaded device to regulate the predetermined pressure.

Referring now to Figure 4, a longitudinal cross-section of the sampler as before mentioned in the description of Figure 1, the body 25 is screwed into the terminating hole of thepassage 20. Passage 2c is therefore continued by passage 20a. The body contains a cylindrical rotor 26 held in place by a cap 21, threaded and screwed over a corresponding thread on the outside of the body 25. The ejectionholes and 31 are aligned so that

passages

29, 3c and 31 are openthruout whenso required. A centrally located pin 2'? is a guide and indicator as will later be shown.

In Figure 6 is shown a cross-section of Figure kexposing the multiple sampling ports 29. As the rotor 26 is revolved, any of the ports 29 are successively brought into alignment with the passage 20d. and rotor 26 may also be turned .so that any of the passages 29 will align with

ejection ports

30 and 31.

In Figure 5 is shown the cap 21 holding the rotor 26 in such a positionthat passage'29 continues the opening 2%. The guide pin 27, firmly attached to the body 25,.formsa pointer to indicate when passages29 and 20a are in line, as the cap 21 is solid. Ejection point 31 is shown in line with one of the passages 29.

Figure 7 shows an inner View, the bottom of the sampler, the passages 29 and 200. being in line, as are

passages

29 and 30.

Referring now to my application for Letters Patent, Serial Number 533,430, da ed April 28, '1931, the seventh law of friction, which states:

7. Friction is inversely proportional to the rate of seepage how at the surface of contact between a solid moving and a porous elastic structure, up to the point of saturation.

Interpreted for plastic packing, the foregoing leans that unless seepage under pressure can flow thru the packing, the friction will rise-due to the tendency to occupy a larger volume, until the saturation point stops any further increase.

The usual method of using plastic packing is to force the material into'grooves or reservoirs, the fact that a den e body having fine pores and interstices will become highly saturated, being overlooked. Plastic materials trap pressure-and unless the material is in thinsections and intercommunication is established from one part to another, the pressure cannot drop uniformly,

which results in blowing the material out at the points of the greatest pressure change. In Figure 1, the

lands

23 and 24 are heroin employed to break the continuity of the plastic'body in-a direction parallel to the pressure flow, which causes seepage to flow across each-of the *thin sections.

The arrangement being made so that seepage does flow, the usage of pressure reaction as-later explained, is made possible, as where there is a drop of pressure ,in a packing :section, Jfriction is created by a net thrust in the direction of the unbalanced pressure. Saturation, as it aifects plastic bodies, will overcome the foregoing mentioned effect.

In disclosing the operation of this device, the location and disposition of the plastic material 32 is indicated in Figures 1, 3, i and 6, such views apparently being ample for explanation. To start, the grooves 22 may be filled with a suitable plastic material before the sleeve 6 is inserted in the stufiing-box chamber 1. Or the needle valve 13 may be opened and the plastic be-placed in the reservoir of the valve body 12 Hand forced thru the continuous passages 19, and

'so into grooves 22. Placed under pressure the .plastic material will flow into all of the grooves 19 and be retained on the inner end of the sleeve 6 by'the disc 9. The plastic will then flow into the

passages

20 and 20a, so into passages 29, if the latter happen to be in line.

* Afterthe passages and grooves are filled with the plastic material the nut 16 may be adjusted so that sufficient :pressure is maintained inthe homogeneous body to correct the density changes .eifected under vibration of the, machine and plunger. On reciprocating plimgers, the pressure against the packing usually rises to a maximum beginning'withthatpart of the strokecoincident with theopeningof the discharge valves of the machine. The-packing is therefore subjected to shock and must be arranged for a measure of flexibility. If the packing is toohard or too rigid it will not'form a close contact with the plunger surface and leakage will result. If, however, either themacking structure is flexible, or its mechanical,arrangementpermits a movement under the shoclgcontact .with the plunger and packing is close, frictionislessand thepacking-will last longer.

In this invention employing a homogeneous mixture of packing materials, .the density of the packing is maintained by the continuous .right and'left hand grooves. ,Asthe pressure rises, the plastic material in each groove is forced back: ward and at an angle with its original position; it-alsojta'kes thexthrus't of pressure in acenter line .conforming'with the direction of the. groove. Undermining and washing by the liquid passincfrom one part .of the plastic material to another is preventedby the-lands 23 and 24 between each V groove. Eachsection ofplastic material forms a portion of a helical screw, each taking its share of the pressure and friction load.

When the shock of sudden pressure rise comes against this design of packing, the packing will I be compressed in each groove and will move sidewaysfromgits original position, due to the pitch of the helical grooves 22. Thus the plastic is arranged mechanically so that as a structure it can move .under shock, be rearranged momentarily, which isthe equivalent of fabric flexibility. The plasticunderithis design will return to its normal vpositionas quickly asthe-pressure is released.

.Suddenhigh pressures cause leakage past plastic packing before the total area and volume of the pac'kingis acted uponby thepressureto become saturated,.and then when saturated, the volume increases and the packing cannot contract. That is, leakage occurs adjacent to the source of pressure action, before the pressure can saturate and change the shape or volume of the packing and force it against the rod. To stop this leakage along the rod, the sealing mustbe done at the source-of pressure and practically coincident with=the rise of pressura'to-protect the packing from cutting and washing. In the helical grooves built according to this invention, the surface of each groove facing the source of pressure is formed into a lip having an acute angle with the rod surface, so that each section of material will be self-set against the rod by any unbalanced pressure at the point of contact. A component of such unbalanced pressure also acts at an angle with the surface of the rod coincident with the rise of pressure. Sealing of the packing at the source of pressure is never later than the rise of pressure and leakage is prevented. If a vacuum on intake strokes occurs before a pressure rise, the opposing lip will seal the joint. As both the faces of the grooves 22 and the lands 23 and-24 are lipped, all of the plastic packing ring sections are subjected to the self-setting action, and the reservoir should be disconnected by closing the needle valve 13 for intermittent or quickly changing pressures. The increase and decrease of saturation is assisted by the interposed lands which break the plastic body into sections, none of which may be considered continuous.

Plastic packing when confined in grooves becomes hard after a period of use, the finer particles are washed or rubbed away, the coarser particles remaining to form a ma The latter will score the rod and finally loose their original plasticity unless provisions are made to offset the inevitable changes mentioned. In the presence of high temperatures plastic packing becomes hardened due to deposits of carbon and other foreign materials in the machine and becomes inoperative in a short period of time, unless removed.

Another cause of plastic packing becoming inoperative when confined in grooves is the chemical reaction with the liquids handled. Deposits of chemicals out of solution are driven into the packing to form hard compositions unsuitable for packing purposes, due to the loss of flexibility.

In this invention, a sampling device is employed to enable the operator to determine how much packing should be removed and how often. When the sampling passages 29 are aligned with 20a, that much packing may be removed from the grooves 22, and from that point adjacent the source of pressure and temperature, where usage is hardest and hardening will occur first. New packing is injected by the loading device attached to the gland 3, which forces the used packing thru passages 29, the operations being simultaneous and done without hindering operation. After a revoiution of rotor 26 has been made, each movement being accomplished by loosening the nut 21, then turning the rotor 26 to match another passage 29 with the opening 20a, a rod may be pushed thru the hole 31, so ejecting the sample of packing thru the hole as for examination.

In those processes of today involving charges of expensive material which must be processed for a stated interval without stopping operations, the machines handling the materials must not be stopped for change of packing.

It is to be believed that the arrangement of this invention will use plastic packing at its highest emciency, convenience of injection and ejection, and be an assurance of continuous operation, so necessary in that class of work involving high pressure and temperatures, shock, and adverse chemical reaction.

The construction as shown is capable of many variations to meet local conditions, and such changes as are embodied in the following claims I do intend to be within the spirit of this invention.

I claim:

1. A stuffing-box formed around a rod with clearance for said rod, grooves formed in the surface of said stufiing-box wall, means to inject plastic packing materials into said grooves, means to maintain a predetermined pressure within said packing structure, an outlet passage from said grooves connected to a sampler device, said sampler device have a revolvable drum with multiple compartments therein which may be successively positioned to receive plastic packing from said grooves, the plastic packing confined in the compartments of said sampler to be ejected successively.

2. A stuffing-box formed around a rod with a clearance for said rod and subjected to a fluid medium under pressure, a right and a left handed helical groove formed in the surface of said stuffing-box wall, the sides of said grooves being undercut to form lips facing the source of said medium at an acute angle with the surface of. said rod and inclining away from the source of said medium plastic packing in said grooves and means to exert uniform pressure upon said pack- 3. A stuffing-box formed around a rod with a clearance for said rod and subjected to a fluid medium under pressure, a right and a left hand helical groove formed in the surface of said stuffing-box wall, the sides of said grooves adjacent to the source of said medium being formed at an acute angle with the surface of said rod and inclining toward the source of said medium plastic packing in said grooves and means to exert uniform pressure upon said packing.

4. A stuffing-box formed around a rod with a clearance for said rod, a right and a left handed groove formed in the surface of said stufIing-box wall, the sides of said grooves being at an acute angle with the surface of said rod and converging toward said rod and means to force a plastic material through said grooves.

5. A stuffing-box formed around a rod with a feed plastic packing under pressure through said grooves and means to remove a sample of said packing as desired.

6. A stufiing-box formed around a rod with a clearance for said rod, helical grooves formed in the surface of said stuffing box wall, the sides of said grooves converging toward said rod surface, a reservoir containing plastic packing materials compressed to a predetermined degree, and means to force said plastics thru a passage to the helical grooves at said predetermined pressure.

7. A stuffing box formed around a rod with a clearance for said rod, helical grooves formed in the inner surface of the wall of said stuffing box, the sides of said grooves being formed at an acute angle with the surface of said rod, a reservoir 1 containing plastic material compressed to a certain predetermined degree, said reservoir being connected to said grooves, and an outlet from said grooves connected with the end of said box remote from said reservoir from which packing may be removed.

HARLEY T. WHEELER.

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